Novel method to prepare polystyrene-based monolithic columns for chromatographic and electrophoretic separations by microwave irradiation

Zhang, Yu-Ping,Ye, Xiong-Wen,Tian, Meng-Kui,Qu, Ling-Bo,Choi, Seong-Ho,Gopalan, Anantha Iyengar,Lee, Kwang-Pill Elsevier 2008 Journal of chromatography A Vol.1188 No.1

<P><B>Abstract</B></P><P>Microwave irradiation can provide a viable alternative to the traditional means such as ultraviolet light and thermal initiation for the preparation of monolithic capillary columns. Polystyrene-based monolithic stationary phases were prepared <I>in situ</I> in fused-silica capillaries and simultaneously in vials. The column permeability, electrophoretic and chromatographic behavior were evaluated using pressure-assisted capillary electrochromatography (pCEC), capillary electrochromatography (CEC) and low pressure liquid chromatography (LPLC). With an optimal monolithic material, the largest theoretical plates for preparing the column could be close to 18,000 plates/m for thiourea in the mode of pCEC. Furthermore, the influence of the composition of the porogenic solvents (toluene/isooctane) on the morphology of organic-based monoliths [poly(styrene-divinylbenzene-methacrylic acid)] was systematically studied with mercury intrusion porosimetry and scanning electron microscopy. The monoliths which were prepared with a high content of isooctane had a bigger pore size and better permeability, and hence resulted in a faster separation.</P>

The Effect of Transformation on the Virulence of Streptococcus pneumoniae

Zhang Xue-Mei,Yin Yi-Bing,Zhu Dan,Chen Bao-De,Luo Jin-Yong,Deng Vi-Ping,Liu Ming-Fang,Chen Shu-Hui,Meng Jiang-Ping,Lan Kai,Huang Yuan-Shuai,Kang Ge-Fei The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.4

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains Id and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.

Protein Kinase C Mediates the Corticosterone-induced Sensitization of Dorsal Root Ganglion Neurons Innervating the Rat Stomach

( Meng Li ),( Lu Xue ),( Hong-yan Zhu ),( Hongjun Wang ),( Xue Xu ),( Ping-an Zhang ),( Geping Wu ),( Guang-yin Xu ) 대한소화기기능성질환·운동학회 2017 Journal of Neurogastroenterology and Motility (JNM Vol.23 No.3

Background/Aims Gastric hypersensitivity contributes to abdominal pain in patients with functional dyspepsia. Recent studies showed that hormones induced by stress are correlated with visceral hypersensitivity. However, the precise mechanisms underlying gastric hypersensitivity remain largely unknown. The aim of the present study was designed to investigate the roles of corticosterone (CORT) on excitability of dorsal root ganglion (DRG) neurons innervating the stomach. Methods DRG neurons innervating the stomach were labeled by DiI injection into the stomach wall. Patch clamp recordings were employed to examine neural excitability and voltage-gated sodium channel currents. Electromyograph technique was used to determine the responses of neck muscles to gastric distension. Results Incubation of acutely isolated DRG neurons with CORT significantly depolarized action potential threshold and enhanced the number of action potentials induced by current stimulation of the neuron. Under voltage-clamp mode, incubation of CORT enhanced voltage-gated sodium current density of the recorded neurons. Pre-incubation of GF109203X, an inhibitor of protein kinase C, blocked the CORT-induced hyperexcitability and potentiation of sodium currents. However, pre-incubation of H-89, an inhibitor of protein kinase A, did not alter the sodium current density. More importantly, intraperitoneal injection of CORT produced gastric hypersensitivity of healthy rats, which was blocked by pre-administration of GF109203X but not H-89. Conclusions Our data strongly suggest that CORT rapidly enhanced neuronal excitability and sodium channel functions, which is most likely mediated by protein kinase C but not protein kinase A signaling pathway in DRG neurons innervating the stomach, thus underlying the gastric hypersensitivity induced by CORT injection. (J Neurogastroenterol Motil 2017;23:464-476)

Enhanced Performances of Vertical-Structured Green-Band InGaN/GaN Multiple-Quantum-Well Solar Cells with Aluminum Reflectors

Meng-Hua Lai,Zhi-Wei Zheng,Jian Yu,Lei-Ying Ying,Bao-Ping Zhang 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.11

We demonstrated vertical-structured InGaN/GaN multiple-quantum-well (MQW) solar cells with enhanced performances at a wavelength of 510 nm. The enhancement was achieved by using a ptype ohmic mirror with a combined indium-tin-oxide film and an aluminum (Al) reflector inserted beneath the MQW absorption region. In addition, both good ohmic contact and high reflection were observed. The vertical-structured MQW solar cell with an Al reflector exhibited significant improvements in device performances as compared to that without the Al reflector, including a 49% increase in the short-circuit current density and a 56% increase in the power conversion efficiency.

Enhanced CO2/N2 separation performance in HP-Cu-BTCs by modifying the open-metal sites and porosity using added templates

Ping Yang,Rujin Zhou,Youhua Zhang,Shui Cao,Dan Zhang,Hongbing Ji,Linhai Duan,Xiuhong Meng 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.3

HP-Cu-BTCs (CTAB), HP-Cu-BTC(N,N), HP-Cu-BTC(SDBS) series with open metal coordination site Cu(I), cage window sites, tunable porosity, high specific surface area, cavity, etc., were synthesized using cationic surfactant (cetyltrimethylammonium bromide, neutral organic amine, and an anionic surfactant as templates, respectively, A variety of techniques were used to analyze the materials before and after CO2 cycle adsorption at 303K. A high BET specific surface area (1,194.06 m2/g) and total pore volume (0.63 cm3/g) were found in the synthesized HP-Cu-BTC(NN). The synthesized HP-Cu-BTC(N,N) not only has high CO2 adsorption capacity (7.4293 mmol/g) but also good selectivity (37.20) for adsorption separation of CO2/N2. Besides, FT-IR spectroscopy, CO2-TPD curves and adsorption kinetic curve demonstrated that the adsorption mechanism of synthesized HP-Cu-BTC(N,N) was mainly attributable to physisorption and it could be regenerated at relatively low temperature. The mesoporous structure not only improves the uptake capacity but also improves the diffusion and mass transfer of CO2. At the same time, the CO2-TPD showed that the HP-Cu-BTCs may have two major adsorption sites. One is to absorb CO2 molecules through van der Waals forces. The other is the electrostatic interaction of the open Cu sites with CO2. Therefore, the CO2/N2 adsorption selectivity of HP-Cu-BTC(N,N) is significantly higher than that of conventional Cu-BTC. After five consecutive adsorption/desorption cycles, the adsorbents retained an excellent adsorption property. Thus, it is a very good adsorbent for the CO2 capture.

Hepatoprotective effects of loach (Misgurnus anguillicaudatus) lyophilized powder on dimethylnitrosamine-induced liver fibrosis in rats

Qian Zhang,Meng-Meng Shang,Qu-Fei Ling,Xiao-Ping Wu,Chun-Yu Liu 대한약학회 2021 Archives of Pharmacal Research Vol.44 No.8

This study investigates the hepatoprotectiveeffects and the potential therapeutic mechanisms of loach(Misgurnus anguillicaudatus) lyophilized powder (MLP)on dimethylnitrosamine (DMN) induced liver fibrosis inrats. After treatment with MLP (50, 100, 200 mg/kg),alanine aminotransferase (ALT), aspartate aminotransferase(AST), albumin (Alb), total protein (TP) andhydroxyproline (Hyp) levels were detected, to assess thedestruction of hepatocytes and the extent of liver fibrosis. Matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), hyaluronic acid (HA), Laminin (LN),procollagen type-III (PC-III), collagen type-IV (C-IV), andtransforming growth factor-b1 (TGF-b1) contents in serumwere all tested using ELISA kits. Alpha-smooth muscleactin (a-SMA) and the tissue inhibitor of metalloproteinase-1 (TIMP-1) protein contents and distribution wereevaluated using western blot and immunohistochemicalanalysis. MLP significantly decreased the serum concentrationsof ALT, AST, Hyp, HA, LN, PC-III, C-IV, MMP-2,TIMP-1, a-SMA and TGF-b1, while increasing the contentsof Alb and MMP-9. No significant changes on TP serum concentrations were observed. These results suggest thatMLP has anti-hepatic fibrosis effects and its mechanism maybe associated with the attenuation of extracellular matrix(ECM) synthesis, the acceleration of ECM degradation,inhibition of hepatic stellate cells (HSCs) activation andTGF-b1 expression.

Development of Origanum vulgare Cell Suspension Culture to Produce Polyphenols and the Stimulation Effect of Salicylic Acid Elicitation and Phenylalanine Feeding

Yan-Ping Li,Dao-Bang Tang,Xiao-Qiang Wang,Meng Wang,Qing-Feng Zhang,Yuan Liu,Bei-Yun Shen,Jiguang Chen,Zhongping Yin 한국생물공학회 2021 Biotechnology and Bioprocess Engineering Vol.26 No.3

Three types of calli were induced from Origanum vulgare (O. vulgare) aseptic seedlings, and the friable calli with white appearance and high growth rate were further screened and used to develop cell suspension culture to produce polyphenols. Murashige and Skoog (MS) medium with 3.0 mg/L Kinetin (KT) and 0.5 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) was suitable for both O. vulgare cells growth and polyphenols accumulation. To further enhance the polyphenols accumulation, O. vulgare cells were treated by phenylalanine (Phe) feeding and salicylic acid (SA) elicitation. Compared with the individual Phe feeding and SA elicitation, SA elicitation combined with Phe feeding showed a much better promotion effect on the polyphenols synthesis in O. vulgare cells, especially rosmarinic acid (RosA) accumulation. With the combined treatment of 200 μM SA and 100 μM Phe, total polyphenols content and yield were 41.36 mg/g and 752.93 mg/L, respectively. RosA content and yield reached 31.25 mg/g and 570.37 mg/L, which were 5.44 and 5.47 times that of the control. Furthermore, the total polyphenols extracted from the cultured cells treated by SA elicitation combined with Phe feeding displayed a much higher antioxidant capacity than that of untreated cells, meanwhile its 1,1-diphenyl-2- trinitrophenyl hydrazine (DPPH) and superoxide anion radical-scavenging activity were much stronger than that of vitamin C. What’s more, our results also showed that RosA was the principal contributor to the fine antioxidant capacity of the total polyphenols extracted from the SA and Phe treated cells. Our research indicated that SA elicitation combined with Phe feeding significantly improved the polyphenols yield and antioxidant capacity of the cultured O. vulgare cells, and therefore has a promising application prospect in natural polyphenols production.

Omnipotent phosphorene: a next-generation, two-dimensional nanoplatform for multidisciplinary biomedical applications

Qiu, Meng,Ren, Wen Xiu,Jeong, Taeho,Won, Miae,Park, Geun Young,Sang, David Kipkemoi,Liu, Li-Ping,Zhang, Han,Kim, Jong Seung The Royal Society of Chemistry 2018 Chemical Society reviews Vol.47 No.15

<P>Phosphorene, also known as single- or few-layer black phosphorus (FLBP), is a new member of the two-dimensional (2D) material family and has attracted significant attention in recent years for applications in optoelectronics, energy storage and biomedicine due to its unique physicochemical properties and excellent biocompatibility. FLBP is regarded as a potential biological imaging agent for cancer diagnosis due to its intrinsic fluorescence (FL) and photoacoustic (PA) properties and negligible cytotoxicity. FLBP-based photothermal and photodynamic therapies have emerged with excellent anti-tumour therapeutic efficacies due to their unique physical properties, such as near-infrared (NIR) optical absorbance, large extinction coefficients, biodegradability and reactive oxygen species (ROS) or heat generation upon light irradiation. Furthermore, FLBP is a promising drug delivery platform because of its high drug-loading capacity due to its puckered layer structure with an ultralarge surface area, and FLBP is size-controllable with facile surface chemical modification. Because of the marked advantages of FLBP nanomaterials in biomedical applications, an overview of the latest progress and paradigms of FLBP-based nanoplatforms for multidisciplinary biomedical applications is presented in this tutorial review.</P>

The Effect of Transformation on the Virulence of Streptococcus pneumoniae

Xue-Mei Zhang,Yi-Bing Yin,Dan Zhu,Bao-De Chen,Jin-Yong Luo,Yi-Ping Deng,Ming-Fang Liu,Shu-Hui Chen,Jiang-Ping Meng,Kai Lan,Yuan-Shuai Huang,Ge-Fei Kang 한국미생물학회 2005 The journal of microbiology Vol.43 No.4

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains 1d and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.

Crystalline Bilayer Graphene with Preferential Stacking from Ni-Cu Gradient Alloy

Gao, Zhaoli,Zhang, Qicheng,Naylor, Carl H.,Kim, Youngkuk,Abidi, Irfan Haider,Ping, Jinglei,Ducos, Pedro,Zauberman, Jonathan,Zhao, Meng-Qiang,Rappe, Andrew M.,Luo, Zhengtang,Ren, Li,Johnson, Alan T. Ch American Chemical Society 2018 ACS NANO Vol.12 No.3

<P>We developed a high-yield synthesis of highly crystalline bilayer graphene (BLG) with two preferential stacking modes using a Ni-Cu gradient alloy growth substrate. Previously reported approaches for BLG growth include flat growth substrates of Cu or Ni-Cu <I>uniform</I> alloys and “copper pocket” structures. Use of flat substrates has the advantage of being scalable, but the growth mechanism is either “surface limited” (for Cu) or carbon precipitation (for uniform Ni-Cu), which results in multicrystalline BLG grains. For copper pockets, growth proceeds through a carbon back-diffusion mechanism, which leads to the formation of highly crystalline BLG, but scaling of the copper pocket structure is expected to be difficult. Here we demonstrate a Ni-Cu gradient alloy that combines the advantages of these earlier methods: the substrate is flat, so easy to scale, while growth proceeds by a carbon back-diffusion mechanism leading to high-yield growth of BLG with high crystallinity. The BLG layer stacking was almost exclusively Bernal or twisted with an angle of 30°, consistent with first-principles calculations we conducted. Furthermore, we demonstrated scalable production of transistor arrays based crystalline Bernal-stacked BLG with a band gap that was tunable at room temperature.</P> [FIG OMISSION]</BR>